Its actually very simple Valkryst.:
NPC has modelid. (creature_template)
Modelid has displayID which has the same ID as displayID, well, sually. - (creature_model_info)
DisplayID store model from CreatureModelData.dbc and "extra" data from CreatureDisplayInfoExtra.dbc - (CreatureDisplayInfo.dbc)
Extra info contains hair and such things and also displayIDs of items. HOWEVER, those displaIDs of items are used ONLY for selecting correct geosets used by models (excluding model items). To make (texture) items themselve appear on model correctly, you need to edit texture BLP, which is stored in last column of DBC.
Now, back to our topic. You need to:
1. get NPCs displayID by .npc info command
2. open CreatureDisplayInfo.dbc on row with your displayID and take a look what its extra ID (#4 column) is
3. open CreatureDisyplayInfoExtra.dbc on row withou your extra ID and look on last column for texture name
Now you can either:
4a. extract texture with that name from patches, it will be in Textures/BakedNPCTextures/ folder and remake it
or:
4b. create your own texture by using WMV (dress character model and use File>Export Model>X3D for getting model's texture), place its BLP version into Textures/BakedNPCTextures/ and change texture name in ..Extra.dbc
For more info check wiki:
http://www.wowdev.wiki/index.php ... ayInfo.dbc - NPC displayIDs
http://www.wowdev.wiki/index.php ... oExtra.dbc - extra data for displayIDs
There was also somewhere a tutorial here for making custom NPC displayIDs, finding and checking it might help you as well.